Various devices of this type in which the bore in the body is formed with a plurality of grooves so that the body can be mounted onto the fastener in any selected one of a plurality of positions are described in earlier patent specifications GB 2242720 A, GB 2325502 A, GB 2335720 A and GB 2409251 A. In GB 2242720 A a safety device is disclosed comprising a simple annular body, the bore of which has plural grooves as aforesaid, which body has a projecting pointer so that when the body is fitted over a hexagonal wheel nut any rotation of the nut, i.e., any loosening of same, will be indicated by movement of the pointer away from a particular initial position which may be towards a marker or towards an adjacent device on an adjacent wheel nut. GB 2335720 A and GB 2325502 A disclose a development wherein a dust cap is incorporated into such a device either integrally or as a separable component. Such devices are now widely used on heavy goods vehicles as a safety measure to indicate any loosening of their wheel nuts. Similar devices are also used as component parts of an assembly comprising multiple such rotation indicators and a ring-like holder for same, as described in GB 2393487 A and GB 2409251 A.
Wheel nuts may be of different sizes, the two most common for HGV being 32 mm and 33 mm across the flats. Accordingly, devices of the types just mentioned, which are commercially available under the registered trade marks “Checkpoint” and “Dustite”, are produced in at least two sizes for snug fitting to at least these sizes of wheel nut so that the angles of the respective hexagonal nuts fit closely into relevant grooves in the bore of the device. Wheel nuts of 31 mm and 34 mm are also known, and further “Checkpoint” devices of suitable bore size and groove size/spacing are, although less common, produced to fit these for indicator purposes.